• 대한치과기공학회지
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• 제30권2호
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• pp.47-56
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• 2008

This is a research for thickness change of denture base according to the shape of sprue & investment position of denture base in flask when injecting polyamid base resin for flexible partial denture as a part of study for Valplast among the flexible partial denture with a nylon base. It has been introduced several kinds of flexible partial denture product with a nylon base, but Valplast is the most widely used product among them. Valplast has been the most generally used material today since developed in 1950s in the United States as a material for flexible partial denture. Valplast is much more aesthetic than general metal-acrylic partial denture due to its translucent pink color and biocompatibility in terms of material characteristic. It keeps its flexibility for a long time after production, imposes a less burden on the teeth used as abutment, and it can be easily insert and remove due to its particular suppleness. Moreover, it is felt like real teeth more than metal-acrylic partial denture when being put in and takes alveolar bone under good protection since it receives occlusal force equally under the denture base. The most outstanding feature of Valplast is flexibility. The extent of its flexibility is determined by width & thickness of denture base. Considering general working procedure of Valplast, it can be seen that the thickness of denture base formed out of wax is increasing by the pressure while injecting resin. This research is to decide and test on the thickness increasing of Valplast by injecting pressure and the hypothesis upon that and is to prepare the basis estimating the increasing extent of thickness of denture base on the basis of the test result. In this test, it is expected occlusal malposition & thickness increasing of denture base by injecting pressure according to 4 kinds of test data which are to select 3 types of sprue method settling the forefront position at which the test material of fixed standard can be invested and to position the test material at the rearmost part keeping the minimum distance to set sprue. For 4 kinds of injecting test by investment position & sprue type, 20 test materials, 5 for each test were produced and a pressure of 1,180Kg was given with automatic injector of air cylinder type. The results are as follows: 1. For the amount of thickness increasing of denture base by investment position, the thickness of front investment is less increasing than the one of rear investment. 2. For the amount of thickness increasing of denture base by sprue type, the thickness of straight decompression sprue type which can absorb the injecting pressure after injecting polyamide base resin is less increasing than the other sprue types.

• 수산해양기술연구
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• 제20권2호
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• pp.137-142
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• 1984

수평관내 증기분무류의 응축열전달에 관하여 실험을 행하고 상당 Reynolds수를 근거로한 열전달효과와의 비교에서 그 결과를 요약하면 다음과 같다. 1. 관내 응축증기 분무류일 경우의 벽면전단응력의 식은 다음과 같이 쓸 수 있다. root($\tau$하(0)/$\tau$하(0v))=1+1.46X 하(tt) 상(0.20). 2. 분무류의 응축열전달효과가 상당 Reynolds수에 의한 값보다 대체로 낮게 나타난 이유는 관내 반경 및 길이방향의 불균일한 액막형성에 의한 Reynolds수 측정값의 차이 때문이다. 3. 분무류의 응축열전달효과에 의한 N sub(u)의 값은 다음과 같다. N 하(u)=1.08$\times$[{$\rho$ 하(l) d/$\mu$ 하(l)}/{$\delta$+(2.5/P 하(rl)) ln(y 하(i)/$\delta$)}]$\times${$\tau$ 하(0)/ $\rho$ 하(l)} 상(1/2)

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2002년도 학술.기술논문발표회
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• pp.23-27
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• 2002

Waterproofing is one of the important factor to improve performance of building elements. But existing repair system for waterproofing have many problems like a damage of waterproof layer due to movement of concrete substrate, blistering effect and moisture condition. So waterproofing layer can not play an important part to improve waterproofing function and performance of building. Therefore, new waterproofing system to solve these problems of existing waterproofing system is developed. In this paper, new waterproofing system in water-leakage repair for remodeling is introduced

• 수산해양기술연구
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• 제30권2호
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• pp.109-115
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• 1994

This paper presents a new concept to reduce turbulent frictional drag by injecting micro-bubble into near the buffer layer of turbulent boundary layer on flat plate. The concentrations of micro bubble distribution in the boundary was calculater by eddy viscosity equations in the governing equations. When near region of the buffer layer of turbulent boundary layer is filled with micro-bulle of air and viscous of the region is kept low, the velocity profile in the near region should be changed substantially. Then the Reynolds stress in the region becomes less, which guide to lower velocity gradient there. It results in reduction of velocity gradient at the viscous sublayer, which gives the reduction of shear stress at the wall.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.241-242
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• 2019

This technology is a water leak repair technology using composite materials of concrete structures that block leakage of structures by injecting rapid microcement into the face of underground concrete to block water and injecting flexible glycidylacrylate. Rapid micro cement system repair materials are mixed with fine fibers to improve the flexural sensitivity of the material and to form a layer that blocks stabilized water at the back of the structure by allowing rapid and tight spatial filling during injection with high cohesion The glycidylacrylate repair material can control the expansion rate, and the external stress also has the characteristic that the form of the material is not destroyed or separated, which can also be applied to vibrating induced structures that produce repetitive fatigue loads, and has an effective durability in saline, alkali, acid (chloric acid, sulfuric acid, nitric acid).

• Corrosion Science and Technology
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• 제12권4호
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• pp.191-197
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• 2013

This study is the second stage of developing the corrosion control technical manual about unpainted weathering steel bridge with closed box girder structures. This paper contains selection of corrosive sealant to apply into crevice of upper flange, injecting test of sealant at mock-up equipment with various condition, evaluation of experiment result. Through the experiment of injection of sealants into crevice of mock-up equipment, it is proved that the tar sealant injecting corrosion control method is useful to protect corrosion at box girder upper flange corroded by remaning rain water with calcium chloride.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 금형가공 심포지엄
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• pp.76-83
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• 2002

The injection molding of the plastic optics is basically same as the conventional molding except it requires very intricate control of all the molding processing parameters. In the plastic optics, the problem of injection molding is the shrinkage. The shrinkage must be removed and predicted. This shrinkage is becoming more important than any other problems in precision molding because it can affect the focal length of a lens or the total performance of the optical system. This study focused on avoiding the shrinkage that the mold design allows for the optics. In making mold, the surface accuracy(P-V) of the lower and lower mold are $0.201{\mu}m\;and\;0.434{\mu}m$ respectively. A surface roughness(Ra) is below $0.02{\mu}m$ due to selecting the appropriate tools and using the injection molding machine in high degree. In injection molding of the plastic lens, mold temperature, resine temperature and injecting pressure are important process parameters. Injection molding process is carried out according to varying mold temperature and injecting pressure. As a result P-V(peak to valley) of spheric lens is $3.478{\mu}m$ and that of aspheric lens is $1.786{\mu}m$.

• International Journal of Automotive Technology
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• 제6권3호
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• pp.215-219
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• 2005

Liquefied petroleum gas (LPG) has been used as motor fuel due to its low emissions and low cost. A liquid direct injection system into a cylinder was suggested as a next generation system to maximize a fuel economy as well as a power. This study addresses the analysis of the LPG spray injecting from single hole injector. Two different test conditions are given, which are a fully developed spray case with various injection pressures and a developing spray case with ambient pressure variation. The LPG spray photographs are compared with the sprays of gasoline and diesel fuel at the same conditions, and the spray angles and penetration lengths are also compared, and then the spray behavior is analyzed. The LPG spray photos show that the dispersion characteristic depends very sensitively on the ambient pressure soon after injection. The spray angle is very wide in a low ambient pressure condition until the saturated pressure, but the angle is quickly reduced at the condition over the pressure. However, the down stream of the LPG spray shows much wider dispersion and less penetration than those of gasoline and diesel sprays regardless ambient pressure condition.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.128-133
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• 2006

Influence of changing combustor pressure on flame stabilization and nitrogen oxide (NOx) emission in the swirl-stabilized flame with secondary fuel injection was investigated. The combustor pressure was controlled by suction at combustor exit. Pressure index ($P{\ast}=P_{abs}/P_{atm}$), where $P_{abs}$ and $P_{atm}$ indicated the absolute pressure and atmosphere pressure, was controlled in the range of $0.7{\sim}1.3$ for each equivalence ratio conditions. The flammable limits of swirl flames were largely influenced by changing combustor pressure and they showed different tendency compared with laminar flames. Emission index showed maximum value near atmospheric condition and decreased with decreasing pressure index for overall equivalence ratio conditions. R.m.s of pressure fluctuations also showed similar tendency with nitric oxide emission. By injecting secondary fuel into flame zone, the flammable limits were extended significantly. Emission index of nitric oxide and r.m.s. of pressure fluctuations were also controlled by injecting secondary fuel. The swirl flames were somewhat lifted by secondary fuel with high momentum, hence low nitric oxide emission. This NOx reduction technology is applicable to industrial furnaces and air conditioning system by adopting secondary fuel injection.

• 전력전자학회논문지
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• 제18권3호
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• pp.279-288
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• 2013

This paper proposes a improved speed control system for five-phase squirrel-cage induction motor(IM) injecting 3rd. current harmonic components with field oriented control (FOC) A five-phase IM drives present unique characteristics due to the additional degrees of freedom and also drives possess many others advantage compared with the traditional three-phase motor drive system, such as reducing a amplitude of torque pulsation at low frequency and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated windings. The produced back-electromotive force is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus third harmonic of currents. There is necessary to controlled 3rd harmonic current in order to high response characteristics. For presenting the superior performance of the proposed the speed control system, experimental results are presented using a 32-bit fixed point TMS320F2812 DSP with 1.5[kW] induction motor.